Now we are ready to take advantage of one of the unique capabilities of the helicopter:
the ability to remain in the air while staying over a point on the ground, also called
hovering. This exercise will build on the coordination of controls that we worked on in
basic maneuvers and approach/departure, and really rely on your skills because we will be
so much closer to the ground.

Hovering Maneuvers

Hovering involves more than just keeping the aircraft stationary over a point on the
ground, but rather encompasses just about all the activities involved when operating in
close proximity to the ground. Except for an occasional glance at your engine instruments,
your eyes should be focussed outside the cockpit while performing these ground
reference maneuvers. These maneuvers include: picking up and setting down of the
aircraft, actual in-ground-effect hovering, forward, rearward, and sideward translation,
pedal turns, and turns about the tail rotor.

For these exercises we will assume a helicopter of western manufacture. That means
that, as viewed from above, the rotor will turn counterclockwise. Russian and French
helicopters (and some homebuilt helicopters) have rotors which turn clockwise, and this
makes a difference when applying pedal changes with changes in power or lateral trim
during speed changes because of dissymmetry of lift. We can expect to apply left pedal
with increases in power, and right trim with increases in speed.

Hover In Ground Effect

If you ever review the specifications for a helicopter, you may come across the
acronyms HIGE (for hovering in ground effect) and HOGE
(hovering out of ground effect). These terms are typically applied when referring to
operating ceilings for aircraft, and relate to the power available from the engine(s).
Just like the wings of an airplane, there is a ground effect associated with operating a
helicopter resulting from the interaction of the downwash from the rotor with the ground.
To some extent, this offers an induced power increase and we will make use of it. Ground
effect is typically present within an altitude of one rotor diameter, and is less
effective when over water or high grass because these surfaces absorb some of the downwash
energy.

You may wonder why you should be concerned about a HIGE ceiling, but if you are
operating at a high gross weight or at a high altitude airport or in high temperature
situations, it is the limiting factor to your ability to get off the ground. You may
attempt a running takeoff (which can involve dragging your skids along the ground for a
good distance) to exploit the effects of effective translational lift in these
circumstances. Just remember to control your direction with the pedals. We will briefly
address HOGE later, although the utility of this maneuver is somewhat lost in a
simulation.

Pick Up

X-Plane sets you up at zero power at the end of a runway. Now what? Obviously we need
to get the aircraft up into the air. For this first time, slowly increase collective to
about half of total power. Move the cyclic very slightly and note the aircraft response.
The object here is to determine just how light the aircraft is on its landing gear. Get
some idea of how this feels and how far along the aircraft is. Continue to increase
collective and add pedal proportionately. Note that the aircraft may not leave the ground
evenly. That is, you may have one part of the landing gear still in contact
with the tarmac after the rest has broken free. This is normal, and you shouldnt try
to compensate for this. You should be concerned with how fast you are climbing (not very)
and whether you are moving in any particular direction.

It should take you at least 5 seconds to get power up to half way, and another 5
seconds to get power up to where the aircraft breaks free of the ground. Breaking the
aircraft free of the ground is similar to two effects in driving: backing out of a parking
spot and engaging the clutch, only you are working in four directions that must be
coordinated precisely.

Remember how when you back a car up from a start and you really have no idea how the
wheel is turned? You must figure this out before you are going too fast so you dont
hit the car next to you. Similarly, when lifting off the ground you must figure out where
the cyclic and pedals located compared to where they need to be. Will you roll left or
right, move forward or backward? Will you begin yawing left or right? You must figure this
out just as the aircraft leaves the ground.

When engaging the clutch on a car, you must figure out if you have the right amount of
accelerator depressed so you dont stall the engine or cause it to overspeed and
jerk. Similarly, you must ensure that you have a very smooth application of collective to
avoid jerking the aircraft into the air and possibly drooping the rotor speed.

So now we have successfully brought the aircraft into the air. Try to achieve a hover
at about 5 feet (the radar altimeter may come in handy here, if you choose to employ it).
Just try to stay at a constant location over the ground. There should be no forward or
rearward motion, and the aircraft should not be drifting to one side or yawing. Make very
small corrections and stabilize yourself in the hover.

Now lets try this again. You can try setting the aircraft down on the ground (we
will discuss this in a bit) by reversing the above control movements just make sure
you are moving forward a bit as you touch down, or re-start your situation from the menu
bar. This time around you should have a better idea of where the controls will be as you
break free of the ground, so you can spend less time playing with cyclic and pedals as you
raise collective.

Part of the fun in flying helicopters is the ability to land on and depart from sloping
ground. Each particular helicopter will have limits based on control authority and landing
gear capability that will limit the degree of slope that you can operate on. We will
address this a little more when we talk about set down, but it isnt an essential
skill for simulator flying.

Pedal Turns

Since you have mastered lifting off the ground and stabilizing the aircraft, you can
essentially hover. From your position five feet off the ground, slowly apply right pedal.
The aircraft should turn to the right. Add some more pedal and make it turn a little
faster. Now reverse pedal motion to stop your turn and try stabilizing in a heading 90
degrees from where you started.

One thing you may have noticed is that the aircraft gained a little altitude. There are
two reasons for this. The first is that the right turn is accomplished because you have
reduced the power required by the tail rotor. That is, a right turn is the natural
reaction to the torque provided by the rotor (remember how you apply left pedal as you
increase collective?), so you are reducing the tail rotor pitch. With a constant
collective setting, this leaves a small amount of extra power to be devoted to a climb.
Also (and this is a small effect), you are adding to the effective rotational speed of the
rotor, increasing lift. Climb speed records for helicopters have typically taken advantage
of this and the pilots have knowingly not applied anti-torque as collective is applied.

Try a left pedal turn and note how the aircraft sinks a little because of the increased
power draw of the tail rotor. I recall a recent accident where the crew attempted a
departure from a confined area on a hot day with a heavy aircraft. They entered a high
hover and applied left pedal at the top. As they watched rotor speed decay, all they could
do was control attitude as the aircraft settled back to the ground, which it did rapidly.

Try turning 360 degrees in your direction of choice. Do this slowly, and in 90 degree
increments. Be particularly careful as the tail rotor faces into the wind, as it will try
to turn you around rapidly. You might try increasing the environmental wind and
experimenting with the aircraft response here. In smaller helicopters, control will
probably be lost as the wind exceeds 20 kts. Now try facing downwind. The aircraft will be
even more prone to weathervaning. Keep making small pedal controls as required
to keep the aircraft in control. Keep your yaw speed under control as you complete the
turn to face into the wind, and apply opposite pedal to stop the turn. Repeat this in the
opposite direction.

Sideward and Rearward Translations

From a hover, move the cyclic slightly backward. As always, make your inputs slowly,
confidently, and deliberately. Maintain track using the pedals. Then apply forward cyclic
to stop the motion and regain your hover.

Now move the cyclic a little to the left to translate the aircraft in that direction.
Again, maintain your track using the pedals. Move the cyclic to the right to arrest your
motion. Once you have regained the hover, move the cyclic some more to the right. Stop
anytime you feel ready.

Combinations

Here are a few exercises that will put the translations together. Select an area on the
airfield that will give you good ground references. The apron area near a hangar or the
end of a runway should be fine. The goal will be to define a square with the aircraft
movement.

Face into the wind near an edge defining tarmac and grass. Move forward several feet.
Arrest this motion and move across the tarmac. When you get to the edge, stop again. Now
move rearward as much as you moved forward. Finally, move back across the tarmac to the
start position. Now try doing this in the opposite direction.

Now try a sideward movement of the aircraft across the tarmac. When you reach the edge,
do a 90 degree pedal turn so you face into the tarmac and continue moving sideward. Repeat
this at each corner, and try it in the opposite direction when you reach your starting
point.

Lastly, move forward along the edge of the tarmac. When you are ready, do a 90 degree
pedal turn and move forward across the tarmac. At the far edge, do another 90 degree turn.
Continue in this fashion until you reach the start, and repeat in the opposite direction.

If you are feeling particularly confident, try moving the aircraft in a circle with the
nose pointed at the center. If you sense a need to truly be humbled, try moving the
aircraft in a circle with the tail pointed at the center.

Set Down

Before we can end our flight and pay our huge helicopter rental bill, we must set the
aircraft back down on the ground. Start in a stable hover and slowly lower the collective
just a bit. Notice how the aircraft descends, but might not quite be touching the ground.
It is important to have no sideward or rearward motion here, and at most just a bit of
forward motion. Wait until your hover stabilizes at this new power setting and lower
collective a bit more. Just as in lift off, one part of the landing gear will touch down
first. Anticipate this, and continue to slowly lower collective until the aircraft is
firmly on the ground. Now you can lower collective all the way. Try lifting the aircraft
up and setting it down with crosswinds and tailwinds.

When setting the aircraft down on a slope, it is important to do so with the aircraft
facing across the slope. That is, the nose will not be facing either up or down the slope.
Start by placing the uphill gear on the ground first. Begin lowering collective, and as
the aircraft begins to roll downhill, apply cyclic control slightly uphill. Continue
lowering collective and moving cyclic uphill until the downhill gear is on the ground.
Keep the cyclic toward the uphill side as you completely lower collective.

I remember one instructor who asked if I was interested in seeing what it felt like to
run out of cyclic control authority while landing on a slope. Of course, I declined. We
picked a small mound of earth and he proceeded to do a slope landing. We ran out of cyclic
before the downhill skid touched down, and hovered there for a few moments. He asked what
I would do if I ever found myself in this situation, and I told him that I would find
another spot.

Hover Out of Ground Effect

High performance helicopters typically only accomplish hovering out of ground effect.
This operation is useful for handling external loads for construction work and helicopter
logging, and for search and rescue. The maneuver is somewhat difficult compared to HIGE
because you no longer have reference to the ground, but still want to remain over a spot
on the ground. Specifications for US Army helicopters often require an ability to hover
out of ground effect at 4000 feet on a 95 degree day at a specified weight.

There are two hazards associated with hovering out of ground effect. The first concerns
an operating limit of the aircraft based on its ability to successfully enter an
autorotation based on airspeed and altitude, and is defined by the height-velocity
diagram for a given aircraft. This diagram is often referred to as the
deadmans curve and we will review it when we talk about autorotations.
The second concerns the aircraft falling into its own downwash. The situation is called
power settling. If collective is lowered and the aircraft does begin settling,
raising collective may not have any real effect so the aircraft will continue to fall.

Quick Stop

The quick stop is a maneuver of little use, but it does give a good lesson in control
coordination and this is a good place to discuss it. From a hover, accelerate to 50 kts
into the wind and climb to 50 feet. When you are ready, begin decelerating and descending
to a normal approach to your selected spot on the ground.

Advanced Systems

As difficult as hovering seems to be, the big aircraft have it a little easier. These
aircraft may include systems that can set an aircraft up for an approach to a hover or
even maintain a hover by taking advantage of automatic flight control systems, stability
augmentation systems, and advanced avionics such as Doppler radar coupled to the flight
controls. Some aircraft include displays that show hover-related information such as drift
and accurate height. The pilot can maneuver these aircraft without having to look outside,
or even with hands off the controls.